1. Field of the Invention
The invention relates to a high-temperature superconductor arrangement comprising a layered ceramic high temperature superconductor
2. Discussion of Background
DE 4418050 A1 disclosed a hollow cylindrical high-temperature superconductor which has a wall thickness of 3 mm and is suitable for current-limiter applications and which may be coated on one or both sides with a 1 xcexcm thick silver layer. Applied to the latter or directly to the internal surface of the high-temperature superconductor may be a 10 xcexcm thick 2nd metal layer or metal foil of silver or aluminum or a 100 xcexcm thick layer or foil of lead or antimony or indium or bismuth or steel or tin or zinc or of an alloy of said metals. These layers are wrapped around with an elastic steel wire and fixed by a solder or a cold-resistant synthetic resin or epoxy resin.
To use a high-temperature superconductor as current limiter in alternating-current lines, in particular for electrical powers of xe2x89xa71 MW, it is desirable to use an electrical bypass whose electrical resistance is less than that of the high-temperature superconductor in the non-superconducting state since critical hot spots may otherwise occur. In particular, the ceramic high-temperature superconductor should haves a bypass layer whose electrical resistivity is increased by more than 10 times with respect to that of a pure noble-metal bypass layer in order to enable an economical current limiting.
The American Institute of Physics Handbook, edited by D. E. Gray, McGraw-Hill Book Company, New York 1965, 3rd edition, pages 9-42 discloses, inter alia, that the electrical resistivity of bismuth is 30 xcexcxcexa9xc3x97cm at 80 K.
DE 4107685 A1 discloses a superconducting current limiter in which a 2 mm wide or 2 mm thick bifilarly wound ceramic superconductor is connected to a carrier of ceramic, diamond or metal via an electrically insulating layer of zirconium dioxide, strontium titanate or diamond.
Accordingly, one object of the invention, is to improve a high-temperature superconductor arrangement of the type mentioned at the outset so that no separate hot spots occur when it is used as current limiter for electrical powers of xe2x89xa71 MW.